Method and system for pulse measurement

Abstract

A method and system for determining a person's heart pulse rate in noisy environments is provided. The method of determining a person's heart pulse rate includes radiating first and second wavelengths of light towards a tissue, measuring and storing a first and second set of parameter values from the signals reflected back from the first and second wavelengths respectively. The first set of parameter values represents a first signal corresponding to a combination of the heart pulse rate and extraneous noise and the second set of parameter values represents a second signal mainly comprising extraneous noise. The heart pulse rate is obtained by deducting the second set of parameter values from the first set of parameter values.

1 . A method for determining a person's heart pulse rate, comprising:
 radiating first and second wavelengths of light towards a tissue;   measuring and storing a first and second set of parameter values from the signals reflected back from said first and second wavelengths respectively, wherein said first set of parameter values represents a first signal corresponding to a combination of the heart pulse rate and extraneous noise and said second set of parameter values represents a second signal mainly comprising extraneous noise;   deducting the second set of parameter values from the first set of parameter values, thereby to obtain the heart pulse rate.   
     
     
         2 . The method of  claim 1 , further comprising the steps of:
 for a sampling taken over a specific time period, comparing the value of the sample for the first signal from said first set of parameter values, with the corresponding value of the second signal from said sample from said second set of parameter values taken over said specific time period; and   if there is a difference between the first and second sampling values, altering said first and second sampling values by applying weighting coefficients to each of said first and second sampling values.   
     
     
         3 . The method of  claim 2 , further comprising the step of:
 applying a Fast Transversal Recursive Least Squares (FTRLS) filter comprising forward and backward prediction filters to each of the first and second sampling values.   
     
     
         4 . The method of  claim 1 , wherein said first light has a first wavelength and said second light has a second wavelength wherein the second wavelength is different from said first wavelength. 
     
     
         5 . An optical accelerometer comprising:
 first and second light sources for radiating first and second wavelengths of light, respectively towards a tissue;   a sensor for receiving a first signal and a second signal reflected back from the tissue from said first and second light sources respectively, said first signal comprising an AC signal representing the heart pulse rate together with a DC signal and said second signal comprising a DC signal representing movement plus a relatively minor AC signal; and   a filter configured for separating the first signal from the second signal, thereby to determine the movement.   
     
     
         6 . The optical accelerometer of  claim 5 , wherein said first light source has a first wavelength and said second light source has a second wavelength wherein the second wavelength is different from said first wavelength. 
     
     
         7 . The optical accelerometer of  claim 5 , wherein said filter is an adaptive filter configured to applying weighting coefficients to said first and second signals. 
     
     
         8 . The optical accelerometer of  claim 7 , wherein said filter comprises a Fast Transversal Recursive Least Squares (FTRLS) filter, said FTRLS filter comprising a forward prediction filter and a backward prediction filter. 
     
     
         9 . A non-invasive device for the measurement of heart pulse rate and pulse oximetry, comprising:
 first and second light sources for radiating first and second wavelengths of light, respectively towards a tissue;   a sensor for receiving light reflected back from the tissue from said first and second light sources, said received light from said first light source represents a first signal corresponding to a combination of the heart pulse rate and extraneous noise and said second set of parameter values represents a second signal corresponding to the extraneous noise only; and   a filter configured for separating the signal representing the heart pulse rate from signal representing a combination of the heart pulse rate and noise, thereby to obtain the heart pulse rate.   
     
     
         10 . The device of  claim 9 , wherein said filter comprises:
 an adaptive filter for comparing a first value of the first signal from said first set of parameter values, with the corresponding second value of the second signal from said second set of parameter values taken over a specific time period; and   if there is a difference between the first and second values, altering said first and second values by applying weighting coefficients to each of said first and second sampling values.   
     
     
         11 . The device of  claim 10 , wherein said filter further comprises a Fast Transversal Recursive Least Squares (FTRLS) filter, said FTRLS filter comprising a forward prediction filter and a backward prediction filter. 
     
     
         12 . The device of  claim 9 , wherein said first light has a first wavelength and said second light has a second wavelength wherein the second wavelength is different from said first wavelength.